Changes between Version 22 and Version 23 of Tools/Gdb Server


Ignore:
Timestamp:
Dec 7, 2009, 11:14:35 AM (14 years ago)
Author:
Joel Porquet
Comment:

Typos and flags memo section

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  • Tools/Gdb Server

    v22 v23  
    11
    2 = GDB Server for Soclib =
     2= GDB Server for SoCLib =
    33
    4 The !GdbServer tool is a software debugger for !SoClib.
     4The !GdbServer tool is a software debugger for !SoCLib.
    55
    66== Overview ==
    77
    8 The !GdbServer is able to manage all processors in a soclib platform. It listens for TCP connection from [http://www.gnu.org/software/gdb/ Gnu GDB] clients. Once connected, clients can be used to freeze, run, step every processor in the platform, add breakpoints, catch exceptions and dump registers and memory content.
     8The !GdbServer is able to manage all processors in a !SoCLib platform. It listens for TCP connection from [http://www.gnu.org/software/gdb/ Gnu GDB] clients. Once connected, clients can be used to freeze, run, step every processor in the platform, add breakpoints, catch exceptions and dump registers and memory content.
    99
    1010== Implementation ==
    1111
    12 The !GdbServer contains no processor specific code and can be used to manage any Soclib processor model using the generic Iss interface. It is implemented as an Iss wrapper class. When the !GdbServer is in use, it intercepts all events between the processor Iss model and the Soclib platform. This enables the !GdbServer to access platform ressources as viewed from the processor without modifing platform components or processor model source code. The !GdbServer is able to freeze the wrapped processor model while the platform is still running.
     12The !GdbServer contains no processor specific code and can be used to manage any !SoCLib processor model using the generic Iss interface. It is implemented as an Iss wrapper class. When the !GdbServer is in use, it intercepts all events between the processor Iss model and the !SoCLib platform. This enables the !GdbServer to access platform resources as viewed from the processor without modifying platform components or processor model source code. The !GdbServer is able to freeze the wrapped processor model while the platform is still running.
    1313
    14 In order to simpfify the debug in a multi-processor context, all processors wrapped in a !GdbServer will be frozen when a breakpoint is detected in one single processor.
     14In order to simplify the debug in a multi-processor context, all processors wrapped in a !GdbServer will be frozen when a breakpoint is detected in one single processor.
    1515
    1616== Usage ==
    … …  
    137137The gdb client offers a easy way to send server specific data though the `monitor` command. Our GdbServer takes advantages of the `monitor` command to provide useful advanced features:
    138138
    139  * The !GdbServer may be instructed to dump every inter-function branch to produde a calltrace on stderr. The {{{set_loader}}} function must be used on Gdb iss to enable this feature. This can be enabled globally by adding the `C` flag to the `SOCLIB_GDB` environment variable; or on a per processor basis using the calltrace command:
     139 * The !GdbServer may be instructed to dump every inter-function branch to produce a calltrace on stderr. The {{{set_loader}}} function must be used on Gdb iss to enable this feature. This can be enabled globally by adding the `C` flag to the `SOCLIB_GDB` environment variable (or the `Z` flag for dumping only call to function's entrypoint); or on a per processor basis using the calltrace command:
    140140{{{
    141141(gdb) monitor calltrace 0         # disable for all processors
    … …  
    153153(gdb) monitor except 0 2          # disable for thread 2 (processor 1)
    154154}}}
    155  Exception catching is enabled by default but can be disabled globaly by adding the `X` flag to the the `SOCLIB_GDB` environment variable.
     155 Exception catching is enabled by default but can be disabled globally by adding the `X` flag to the the `SOCLIB_GDB` environment variable.
    156156
    157  * An alternative way to set hardware watch point range is provided to bypass the sometime annoying gdb client watch point feature. It can be used to modifiy directly the read and write watching intervals. The following commands set a 4 bytes (default is cpu register width) read/write watch interval at 0x12345678 and then excludes read watching for 32 bytes range at 0x12345000. These watch points will be unknown to the gdb client and will be lost when the simulation terminates.
     157 * An alternative way to set hardware watch point range is provided to bypass the sometime annoying gdb client watch point feature. It can be used to modify directly the read and write watching intervals. The following commands set a 4 bytes (default is cpu register width) read/write watch interval at 0x12345678 and then excludes read watching for 32 bytes range at 0x12345000. These watch points will be unknown to the gdb client and will be lost when the simulation terminates.
    158158{{{
    159159(gdb) monitor watch rw 0x12345678
    … …  
    166166export SOCLIB_GDB_WATCH=0x12340000r:0x45870000rw      # read watch [0x12340000, 0x12340003], rw watch [0x45870000, 0x45870003]
    167167}}}
    168  The `W` flag can be added to the the `SOCLIB_GDB` variable to just repport watchpoint hit on stderr and avoid stoping the simulation to be less intrusive.
     168 The `W` flag can be added to the the `SOCLIB_GDB` variable to just report watchpoint hit on stderr and avoid stopping the simulation to be less intrusive.
    169169
    170170 * The gdb protocol debug mode may be enabled to dump interaction between client and server:
    … …  
    173173}}}
    174174
    175  * The gdb server almost stops the simulation process when the instrumented virtual processors are frozen. This saves ressources of the host machine during debugging sessions. However this behavior may be an issue when freezing other platform components is not desirable (Use of multiple GDB servers with different processors, critical I/O device latency, multi-threaded simulation... ). The `sleepms` command can be used to tweak the simulator sleep time between each execution cycle when the processors are in frozen state. This value may be set to 0 to let the simulation running at full speed or to -1 to completly stop the simulation while processors are frozen. The `SOCLIB_GDB_SLEEPMS` environment variable can also be used to set this value. An integer ms value is expected. The default value is 100ms.
     175 * The gdb server almost stops the simulation process when the instrumented virtual processors are frozen. This saves resources of the host machine during debugging sessions. However this behavior may be an issue when freezing other platform components is not desirable (Use of multiple GDB servers with different processors, critical I/O device latency, multi-threaded simulation... ). The `sleepms` command can be used to tweak the simulator sleep time between each execution cycle when the processors are in frozen state. This value may be set to 0 to let the simulation running at full speed or to -1 to completely stop the simulation while processors are frozen. The `SOCLIB_GDB_SLEEPMS` environment variable can also be used to set this value. An integer ms value is expected. The default value is 100ms.
    176176{{{
    177177(gdb) monitor sleepms 10
    178178}}}
    179179
     180=== Flags memo ===
     181The following flags can be concatenated in the `SOCLIB_GDB` environment variable (eg, {{{$ export SOCLIB_GDB=SZ}}})
     182 * '''F''': start the simulation in a frozen state so it can be attached with a gdb client
     183 * '''X''': disable automatic break whenever an exception is caught, the exception handler will be called transparently
     184 * '''S''': make the simulation stop and wait for a gdb attachment whenever an exception is caught
     185 * '''C''': dump a trace of every inter-functions branch
     186 * '''Z''': same as '''C''' but display only function's entrypoint
     187 * '''W''': disable automatic break whenever a watchpoint is hit, just report it on stderr (the watchpoints are to be defined in SOCLIB_GDB_WATCH)
     188
     189----
     190
    180191More informations on using the GDB client can be found on the [http://sourceware.org/gdb/ The GNU Project Debugger] home page.
    181192